The difference between the proportional counter and the GM counter is in the process of the gas discharge formation within the counter volume. If gas discharge develops over the entire gas volume in the Geiger-Mueller counter, then in the proportional counter gas discharge occurs only in the part of the gas volume. First primary ionization is formed, and then an avalanche of electrons is formed. The remaining volume is not covered by the gas discharge. The amplitude of the signal produced by discharge is proportional to the detected particle energy.